Occupational injury rates have changed slowly since 1981 suggesting that further reduction will require new approaches to supplement understanding about the technical environment and individual behaviors. It has been suggested that a better understanding of work organization may be an important next step. Social network analysis provides a means of quantifying one part of work organization - relationships that affect access to potentially beneficial resources of coworkers. Social network analytic methods will be used to explore the role of the workplace social organization in the incidence of job-related injuries. The study will examine how the social context surrounding the worker modifies the risk of injury by shaping access to the potentially risk-reducing resources possessed by coworkers. In particular, information, physical assistance and social support are hypothesized to be resources that can help workers avoid injury hazards. Social network measurements (sociometrics) are used to quantify properties of work groups and of the way individuals relate to group members rather than properties of individuals, per se. The study population is nurses and nurse aides employed in a long-term psychiatric facility studied prospectively over one year. The exposures, elements of the workers' social networks, will be measured by self-administered survey questionnaires given at three times in order to account for changes in the social network. Employee attendance records, demographic data, and injury data will be gathered from administrative records. Respondents will be asked to identify the coworkers he/she goes to for advice about work, who he/she asks for physical help when needed, and which coworkers he/she consider as friends; the responses are used to construct indices describing the workplace social structure. Statistical methods will be used to test hypotheses that individuals are less likely to be injured; who are a) able to call upon coworkers for information about hazardous procedures and safe practices, b) able to call upon coworkers for physical assistance in hazardous circumstances are less likely to be injured; and c) socially connected to their coworkers. Results are expected to provide a better understanding of social factors in the injury process and is also an opportunity to span the disciplinary boundaries of epidemiology and sociology in order to broaden the range of theoretical and methodological approaches used in the study and prevention of occupational injuries.